Isocyanate compounds are industrially broadly used as materials of, for example, various urethane compounds and urea compounds; and curing agents of resins and paints.
For example, the following methods are known as the method of producing isocyanate compounds.
(1) A method of reacting a primary amine with phosgene. This is mainly used industrially.
(2) A method of thermally decomposing a carbamate compound having —N(H)—C(O)O— in its molecule in the presence of a catalyst (e.g. Patent Reference 1).
(3) A method in which a non-aromatic carbamate compound is obtained by reacting a non-aromatic diamine, which does not have such a structure that the amino groups directly bonded to an aromatic ring, with an alkylaryl carbonate in the absence of a catalyst, and then it is converted into an isocyanate compound by thermal decomposition in the presence of a catalyst (Patent Reference 2).
(4) A method of obtaining an isocyanate compound by thermally decomposing an aromatic carbamate compound having a fluorine atom in its molecule in the absence of a catalyst (Patent Reference 3).
(5) A method in which a carbamate compound having a fluorine atom in its molecule is obtained by reacting a polyamine and a fluorine-containing carbonic diester in the presence of a catalyst, and then it is converted into an isocyanate compound by thermal decomposition in the absence of a catalyst (Patent References 4 and 5).
(6) A method of obtaining an isocyanate compound by a de-chloroform reaction of trichloroacetamides in N,N-dimethylformamide in the presence of sodium carbonate (Non-patent Reference 1).